A typical interior lighting of a motor vehicle includes a lighting device disposed in the vehicle ceiling in the front area of the passenger compartment, emitting an essentially white light. Sometimes, additional light sources are assigned to this lighting device, for instance at the level of a rear seat bench or in the trunk. The interior lighting provides better orientation for persons getting in or out of the car as well as during loading and unloading of the vehicle. It is usually activated by the opening of a vehicle door, or by a central locking system of the vehicle with the aid of a control unit. The interior lighting comes on in response to a vehicle door being opened. After the door is closed, the interior lighting is turned off, directly or by a time delay, this sometimes being coupled to the starting of the engine.
After such a lighting device has been turned off, only an instrument light remains active whose brightness and—as known from European Published Patent Application No. 0 562 332—whose color can be manually adjusted. The instrument light and possibly additional lighting devices for operating controls such as the door handle and cigarette lighter are not used to illuminate the interior and are coupled to an activation of a vehicle's exterior lights.
The current interior-lighting systems for motor vehicles have the disadvantage that they are only activated in connection with the opening of a vehicle door and are turned off by the closing of the door, or by a brief delay, so that the interior remains dark during the predominant part of the actual vehicle operation. If an occupant wants to search for something or read a map in a dark vehicle environment, the interior lighting must be turned on manually, resulting in an attention loss for the traffic situation. Also, the stay in a dark environment is often perceived as unpleasant, and it promotes tiring of the driver as well.
In Japanese Published Patent Application No. 5-270314, an interior lighting for busses is described where a color of the light emitted by the lighting can be changed as a function of an outside temperature. At high outside temperatures, a light perceived as cool is provided and a light perceived as warm when the outside temperature is low. The disadvantage of this design is that an outside temperature bears no relationship to an inside temperature of a subjective temperature perception of an occupant. Therefore, the lighting might even be perceived as distracting, in an extreme case.
It is an object of the present invention to provide an interior lighting for motor vehicles and a method for its control by which it may be ensured that a vehicle occupant is provided with optimum lighting at all times, and thus has a sense of well-being while inside the motor vehicle.